Electric telephone



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ELECTRIC TELEPHONE. Y No.. 244,638. Patented yJuly 19,1881. il

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A W. MAIN. Y y 1 ELECTRIC TELEPHONE. A Nb. 244,638. Patented .Igly 19,1881..

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UNITED VSierras' 'PATENT OFFICE.

. WILLIAMMAIMQF BROOKLYN, NEWIYORK.

ELECTRICYTELEPHON.

SPECIFICATION forming .part of Letters' Patent No. 244,638, datea'qruly 19, 1881. Application liled January 5,1881. (Model.) Y, l u y Y To all whom Muay concern zen of the United States, residing in Brooklyn, in the county of Kings and State oi'New York, lhave invented certain Improvementsin' Electric, Telephones, of which the following is a specification.

rIhis invention relates chietlygfto a battery,`

transmitting-telephone.A Its object is to pro-v vide a telephonewhich is exquisitely sensitive to vocal soundsr uttered in its vicinity without being affected by the extraneous vibrations so frequently occurring coincident] y with speech, and which shall transmit or reproduce speech faithfully and without change of tone.

In the accompanying drawings, Figure lis a side elevation of mytelephone, the inclosin gcase being in section taken in the plane ofthe dotted line 1 1 in Figs. 3 and 4. Fig. 2 is a similar view, the entire telephonebei-ng in section, taken inthe line 2 2 in Figs.`3 and 4.

Fig. 3 is a frontelevation of the telephone, the` case being in section on the'line 3 3 in Figs. l and 25 and Fig. 4 is a rear elevation, the case being in section on the line 4 4 in Figs. land 2. The remaining ligures illustrate modifications. Fig. 5 is a vertical mid-section corresponding'to Fig. 4 and taken on the line 5 5 in Fig. 6. Fig. 6 is a rear elevation with the case in section on the line`6 6 in Fig. 5. Figs. 7 and 8 are horizontal sections in the plane of the line 7 8 in Figs. 5 and 6, illustrating two differentrmethods of making circuit-connections, the inclosing-case being omitted; and Fig. 9 shows another modification, the elements of the telephone beingin side elevation and the circuit-connections being illustrated diagramlnatically.

A is what I shall hereinafter term an acoustic vibrator,77 answering to what in other telephones is called the diaphragm so hung as to be capableof a bodily swinging or back-andforth movement, Whereas diaphragms have invariably been tightly clamped" or otherwise confined at their edges or elsewhere, so that they could vibrate only within themselves, the inexibility resulting from their confined attachment tending to suppress, and'` their own `inherent elasticity tending tov modify -their proper vibration, and prevent them from accu v rately responding tothe form of the sound- Be it known that I, WILLIAMMAIN, a citi-f I mount my vibrator by suspendingit flexi tirely free to vibrate except at the point' or points of' attachment or suspension instead of confining them or mufiing them, as has been f commonly heretofore done. It may be made of any resonant orvibratory material,such as those commonly employed for telephone diaphragms; but I find woodof a resonant quality ypreferable to any other material thatIhave tried, inasmuch as it responds to sound-waves more amply. than others, (owing partly, perhaps, to its greater lightness,) and consequently transmits a louder sound, and it also has the property of transmitting sounds of different pitch more equallythan other materials with` which I have experimented.

f I prefer that the vibrator be in the form of a flat plate orboard, as this is the form by which I have secured the best results; but it may be given other shapes without material detriment to its operation-such, for instance,

as ahollow cone or the segment of a hollow sphere. Instead of its being arranged to stand in a vertical plane it may be inclined backward or forward, resting, when used lillna'battery-transmitter, on the resistancevarying contacts. These modifications, however, are merely possible. I do not consider them desirable. f l. f

In order to confine the sound-waves which approach tllevibrator and direct them onto its surface, Iemploy walls or partitions B, arranged at the front side of the vibrator and standing at substantially right angles to its surface. These walls are preferably attached to and borne by the vibrator, as shown in Figs. l to 4; but they may be otherwise supported out of contact therewith, as shown in Fig.'5.

These walls may consist of a simple rim surrounding the vibrator, or ftheymay. be partitions lor ribs crossing the same, or, as I prefer, both forms may be used together, as shown in Figs. 1, 2, and 3. These walls serve to collect the sound-wavesl and guide them against the vibrator, serving, in this respect, a somewhat similar purpose to the ordinary concave mouthpiece, except that in reecting the sound they do not concentrate it at one point or focus. When fixed to the vibrator they also, to a great extent, prevent it from responding to inaudible vibrations, thus suppressing microphonic effects, and they also serve to suppress the natural or sympathetic tone of the vibrator,

Vso that thc transmitted tones are subject to somewhat less alteration than otherwise. I find that any departure from the right-angle arrangement of these walls, with respect to the general plane of the vibrator, results in a corresponding diminution of their utility. I have secured good results by fixing short paper tubes at close intervals over the surface ofthe vibrator. I prefer that the walls B be made of card-board or thin woodsuch as veneer.

C D are the resistance-varyin g contact-points or electrodes essential to a battery transmitting-telephone, the contact C being borne by the acoustic vibrator A,'and the contact D being carried by an arm, D', which arm issuspended from above, by preference, like the vibrator, though it may be hinged at the side or below. It is hung or connected at such apoint that the force of gravity will cause it to rest lightly against the contact C. I prefer that the arm D and vibrator A be both hinged at or suspended from the same pointinorder that the bodily back-and-forth movement or swinging of the vibrator will not cause the two contacts to rub against or rasp across each other, as would be the case were they hung from different points. This suspended contact D requires no adjustment whatever, being arranged to touch the contact C with the requisite pressure at first, and thereafter being unaffected by changes of temperature or the varying positions of the vibrator.

The contacts C D may be of any suitable material having the proper degree of resistance to the passage of an electric currentsuch as carbon, platina, 85e.

A wire, c, leads from the contact C, and another wire, d, leads from the contact D, both wires forming part of the usual local batterycircuit used with transmitters.

A telephone as sensitive as mine is apt to be aifected by the jarring ot' the building, and by echoes to such an extent as to detract from the clearness ot' its transmission of speech. To overcome this defect I have designed the mounting for the telephone, which I will now describe.

The vibrator A and arm D are suspended from an inert body, E, or one having considerable weight in proportion to its bulk, which is itself supported through the medium of an elastic connection, F, preferably of soft indiarubber. The vibrations affecting the supporting part are not communicated to the body E because of its sluggishness or inertia, but are absorbed before reaching it by the elastic substance F.

*G is an inclosing case or box surrounding the active elements of the telephone, and designed to cut oft` all sounds proceeding from other directions than in front of the vibrator, at which point it is furnished with an opening, G. It may be made of wood or other suitable material. The active elements of the telephone are suspended or arranged inside of it.

H is a muftling-lining of non-vibratory or ksound-deadening material-such as cottonwool, felt, soft rubber, &c.-whose office is to prevent the reflection oi' sound-waves against the sides of the box, thereby suppressing echoes.

I will now more specifically describe the particular constructions shown in the drawings.

Referring tirst to Figs. 1 to 4, the acoustic vibrator A is in disk form, with a rectangular top for convenience of attaching hinge-leaves a a, which engage a horizontal pin or rod, b, xed to the body E. By this means the vibrator is pendulously suspended, and is free to swing bodily backward and forward..v The walls B extend around the vibrator and cross it in two directions, vertically and horizontally. The contact C is held in a cup fixed to the back of the vibrator, and the contact D is held in a similar cup formed at the lower end of the arm D', whose upper end engages the rod b between the hinge-leaves a a. The body E consists of a piece of heavy metal tubing fitted on a rod whose ends projectbeyond it, and havin gdownwardly-projecting ears for engaging the ends of the rod b. The prolonged ends of the upper rod are each engaged by an elastic connection, F, which is a suspending connection consisting of a rubber ring or band, although a piece of soft twine or a very elastic spiral spring might suffice. The connections F F han g from hooks ff,which are secured to the case G. I prefer to set this case on a non-vibratory pad or layer, g, shown in Fig. l, to prevent the jarring of the building or of the shelf or table on which it may rest from being communicated to it. A telephone of this construction is so sensitive to Vocal sounds that ordinary conversation uttered in distant parts of a large room in which it is placed are reproduced in the receiving-telephone at a distant station with perfect distinctness, while at the same time it is so free from microphonic efects that it is not at all influenced by the rumblin gs and jarrin gs ot the building in which it is placed. The transmission of sound is clear and natural, and the speaker need not be stationed close to the instrument.

In Figs. 5 to 8 two sets of contacts, C D, are shown. The effect is not materially different from that of one pair of contacts, but in some instances their use may be desirable. In Fig. 7 the circuit is sho n as divided into two branches, with one gair of' contacts in each branch, and in Fig.8 he two pairs are arranged successively in the. undivided circuit. The former plan secure a somewhat louder sound in the receivingiuistrument than when but one IOO IOS

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pair of contacts is used, and there is less re- 1 E is a simple bar of heavy metal, its ends rest.

sistance f to Vthe passage iofa feeble current,A while the latterplan transmits a more natural 1 but somewhat fainter sound. In these figures'.4

the acoustic vibrator isaplain flat lpolygonal board of thin wood, and thewalls B are separatefrom it, being borne by the case G and projecting in'from theopening G. tor A and rigid arms D are all hung from the inert body E by means of strips of lightflexible material, as shown in Figs. 5 and 6. The body ing on soft yielding cushions of rubber or simi fla-r substance,which are the elastic connections F Fand these rest on-shelves or cleats fixed to the sides of the case.

Fig. 9 shows also two pairs of contacts, but( arranged differentially instead of cumulative] y, one pair being on each-side of 'the vibrator, and each pair being in a separate circuit or branch, with a separate battery in'each branch. The undivided portion of the Vcircuit includes the primary wire of an vinduction-coil, I,` and the line or earth circuit includes the secondary wire thereof, as usual. The arrangement of batteries and circuits is such that when the vibrator A moves or vibrates in one direction and presses together one pair of contacts it sends a current through the induction-coil in'` one direction, whereas when it'moves or vibrates in the opposite direction and presses together the kother pair of contacts it sends ,a current inthe opposite direction through the coil. When ,it is `not in vibration the twoopposite currents willin effect neutralize each other, and as one current is strengthened by the movement of the vibrator the other current is correspondingly weakened. This arrangement is not new with me; but my telephone is especially adapted for this method of connection, inasmuch as its contacts are selfadjusting, whereas heretofore it has been al,- most impossible to properly adjust the two pairs of contacts relatively to each other and to a iixed diaphragm, and the adjustment, when secured, has beenliable to derangement by changes of temperature and other causes.

Instead of using two batteries and one induction-coil one battery and two inductioncoils may be employed, one coil and one pair of contacts` being in each branch of the circuit and the battery in the undivided portion. The line-circuit will then pass successively through both coils.

I make no claim in this application to the combination of this reverse-currentv 'arrangenient with the peculiar features of my telephone as l contemplate making such claim the suloject of a future application for patent.

I make no specific claim in this application to the novel features involved in the modified forms of my invention, but I contemplate coveringsuchfeatures by future applications.

I claim as my invention- 1. The acoustic vibrator or diaphragm of a telephone, unmuftled and unconfmed, and hung or suspended from above and otherwise unstantially as set forth.

swinging backward and forward.

3. Ina transmitting-telephone, an acoustic kvibrator or diaphragm consisting of a `vibrat- 7 5 ing plate supported flexibly at one edge, having'its remaining edges unconned and unmnffled, and bearing upon its back one ofthe resistance-varying contacts or electrodes, sub- 4. In a transmitting-telephone, the combination of an acoustic vibrator or diaphragm, A, supported iiexibly at one side. or edge and otherwise unsupported, and capable of bodily v movement backward and forward,with sound conning and reflecting walls B, arranged in front of said vibrator and at substantiallyrightangles. to the general plane thereof.

5. An acoustic vibrator or diaphragm for a telephone, flexibly supported at one edge or 9o side and otherwise'unsupported, so as to be capable of swinging to and fro, and vprovided with sound receiving and con flnin g walls fixed to and borne by it and `arranged at substantially right angles to the general plane of its surface.

6. An acoustic vibrator or diaphragm for a telephone, flexibly suspended from above and provided on its front surface with light sound collecting and yconfining walls or partitions loo fixed to it at substantially right angles to the general planeof its surface.

7 An acoustic vibrator for a telephone conA sistingzof a board of light resonant wood sus pended iiexibly from above and otherwise unro 5 supported, and provided with sound-confining walls or partitions of light material, as cardboardor veneer, x'ed to it at right angles, or nearly so, substantially as set forth.

8.A transmitting-telephone consisting of 11o an acoustic vibrator supported flexibly at one side and bearing a resistance-varying contact or electrode,in combination with another such contact or electrode, thel two contacts being pressed lightly together by the force of gravity, I I 5 substantially.as` set forth. v

9. A transmittingltelephone consisting of thecom bination of a suspended vibrating plate capable of swinging back and forth, a resistance-varying electrode arranged against the 12o back thereof, audasecond such electrode borne by a part which is also hung or suspended from above, pressed gently against the rst electrode by the action of gravity and capableof swinging with vthe vibrating plate, substan- I2 5 tially as set forth.

10. A transmitting-telephone consisting of an acoustic vibrator or diaphragm supported at one side or edge and otherwise unsupported, and free to vibrate and to move bodily back 13,9 and forth, and vbearing a resistance-varyin g contact, in combination with another such con I tact arranged to lightly touch the rst and borne by a part which is supported from the same point as the vibrator, substantialljy7 as and for the purposes set forth.

11. The combination ofthe acoustic vibrator or diaphragm and resistance-varying contacts of a transmitting-telephone with an inertbody, E, arranged to support saidv parts, and with elastic connections F F, arranged to. support said bod y, whereby said vibrator and contacts are insulated from inaudible vibrations affecting the ultimate support ot' the apparatus, substantially as set forth.

l2. The combination of the acoustic vibrator or diaphragm and resistan(ze-varying contacts of a transmitting-telephonc, with elastic or sound-absorbing suspending connections F F, substantially as and for the purposes set forth.

13. The combination of the acoustic vibrator and resistance-varying contacts of a transmitting-telephone, Wi th a box or case, G, arranged to inclose the same, and a sound absorbing or mufing lining, H, covering the interior sur face ot' the case and arranged out of contact With the Vibrator, for the purposes set forth.

14. The combination of a box or case, G, having a sound-opening, G', a sound absorbing or inutiling lining, H, arranged to cover substantially the entire interior surface of the case, and the acoustic vibrator or diaphragm and resistance-varying contacts of a transmitting-telephone suspended freely within the case and arranged out of contact with said lining, substantially as set forth.

In witness whereof I have hereunto signed my name in the presence ot' two subscribing witnesses.

WM. MAIN.

Witnesses:

ARTHUR G. FRAsER, HENRY CoNNET'r. 

